In the manufacture of glass containers by a process that is often referred to as the flow process, molten glass flows through an orifice at the bottom of a feeder bowl, which is located at the outlet end of a molten glass conditioning forehearth, to a glass forming machine positioned beneath the feeder. In such an arrangement the feeder bowl is at an elevation which is substantially above the elevation of the floor on which the forming machine is positioned beneath the feeder bowl. The rate of flow of molten glass through the orifice of the feeder bowl must be closely controlled to control the weight of the containers being formed by the underlying forming machine, and such control is accomplished by controlling the position of a vertical elongate member, called a needle, relative to the fixed position of the feeder bowl orifice. Typically, in conventional glass container manufacturing operations each feeder bowl will have two or more flow orifices, and each such orifice will be provided with a needle whose position relative to its flow orifice during the flow process must be controlled independently of the positions of the other needles associated with the same feeder bowl. Further, it is customary to provide a mechanism for intermittently retracting each needle from its feeder bowl orifice to suspend flow through the orifice when a shearing mechanism positioned between the feeder bowl orifice and the forming machine is operating to shear the glass stream flowing from the orifice into a series of gobs, each of which is to be formed into a container by the forming machine.
The adjustment of needles in feeder bowls of the type described above, independently of the reciprocation of the needle as required to coordinate feeder bowl operation with shear mechanism operation, typically requires that a glass forming machine operator climb to the level of the feeder bowl, an area where the temperature will often inherently be uncomfortably high, to make a mechanical adjustment in the position of one or more of the feeder needles. Following this, the operator must return to the forming machine floor to weigh freshly formed containers to determine if any further adjustment in the needle position is required, and to return to the level of the feeder to make a further adjustment in the position of one or more of the needles if any of the containers are still not within applicable weight specifications, and to repeat this process until all containers are within weight specifications. Clearly, this is a tedious and unpleasant way to maintain suitable control over glass container weight, and its time-consuming nature precludes the making of needle position adjustments in as timely a manner, or as frequently, as is desirable.
Various glass melting bowl needle assemblies according to the prior art are disclosed in U.S. Pat. No. 4,581,055 (Bratton), U.S. Pat. No. 4,554,000 (Suomala et al.), and U.S. Pat. No. 4,682,998 (Ayala-Ortiz), the disclosure of each of which is incorporated by reference herein.